Which is one of the four exceptions to the Parol Evidence Rule?

• A. To correct a clerical error
• B. To interpret a vague or ambiguous term
• C. To supplement a partially-integrated writing
• D. To establish a defense against formation

Answer: (D)

The Parol Evidence Rule has narrow allowances for evidence outside the written contract, and one important exception covers defenses to the contract’s formation. This means you can introduce extrinsic facts to show the contract never formed or is unenforceable because of issues like fraud, misrepresentation, duress, lack of consideration, or incapacity. If someone argues that the agreement isn’t valid or never came into existence, evidence about those defenses is admissible even though there is a written contract. That’s why this option fits as one of the recognized exceptions: it targets the validity and formation of the contract itself, not the interpretation or supplementation of its terms.

Interpreting a vague or ambiguous term can be addressed with extrinsic evidence in many cases, and supplementing a partially integrated writing is another recognized use, but those are different aspects of how extrinsic evidence can be used. Clerical-error correction usually falls under reformation or separate corrective mechanisms rather than this defense-to-formation exception.